1. Field of the Invention
The present invention relates to the field of switched telephony, and more particularly, to a method and system for integrating wireless telephones into a wireline messaging environment.
2. Background of the Invention
With the proliferation of wireless communication networks, many telephone customers now use a combination of wireline and wireless telephones to meet their communication needs. Indeed, it is not uncommon for a single user to have more than one telephone line at home, more than one telephone line at work, and at least one wireless telephone. Telephone customers have come to depend on the flexibility of this combination to communicate irrespective of location.
However, having multiple wireline and wireless telephone numbers presents problems retrieving telephone messages. Usually, a caller who calls a user who subscribes to multiple telephone lines dials one of the user's telephone numbers. If the user is away from the particular device that is called and does not answer the call, the caller typically leaves a message on a voicemail system. In the past, such voicemail systems have been isolated on the network of the particular telephone line that is called. Thus, to retrieve all messages, a user had to check the voicemail system of each network separately.
Recognizing the trouble of constantly checking multiple voicemail systems, messaging service providers (MSPs) developed voicemail systems that integrate incoming messages across different networks. Thus, for example, a user could direct all messages for her wireline and wireless telephone lines to a single voicemail box. Consequently, the user would need only to check a single voicemail box to retrieve all messages.
According to these standard voicemail systems, a voicemail platform is in communication with a central office switch. The central office switch is in communication with the wireline and wireless networks. Unanswered calls to a subscriber's wireline and wireless telephone numbers are routed to the voicemail platform through the central office. Thus, regardless of the particular telephone number the caller dials, all voicemail messages end up in the same voicemail platform.
Despite providing centralized voicemail boxes, these integrated voicemail services present difficulties in notifying a user of the receipt of a message. Specifically, because all unanswered calls are forwarded through the central office to the voicemail platform, the voicemail platform is responsible for activating message waiting indicators on all of the associated telephones (e.g., a stutter dial tone, an illuminated light, or a displayed icon). Thus, for example, if a user away from his work office receives an unanswered call to his wireline office telephone, and the call is forwarded to the voicemail platform, which records a message, then, ideally, the user would want to receive a message waiting indicator on his wireless telephone to report to him that he has received a new voicemail message. This notification would avoid the burden of constantly checking the voicemail for messages received through a remote telephone. Similarly, if the user is in his office and receives a message through an unanswered call to his wireless telephone, which is turned off or out of range, the user would want to receive an indication of the message on his office wireline telephone.
To provide message waiting indicators on all of a user's associated telephones, wireline network providers developed methods for supporting messaging from the voicemail platform to a “foreign network.” As used herein, “foreign network” refers to a network that is not local to the network including the central office switch that serves the message provider. This local central office switch is sometimes referred to herein as the host switch.
FIG. 1 illustrates a typical method and system for providing messaging from a voicemail platform to a foreign network. Messaging service provider 100 contains a telephone list 102 indicating telephone numbers that a subscriber to the messaging service has associated with her voicemail box. An unanswered call to any of the listed telephone numbers is routed to messaging service provider 100 for the recording of a message and the indicating of the recorded message. In this example, the subscriber has associated with the messaging service a wireline telephone number, 404-332-212X, and two wireless telephone numbers, 404-792-123X and 404-792-100X.
Telephone list 102 also contains an activation flag indicating whether the subscriber has subscribed to the message waiting indicator (MWI) feature for the particular telephone number (device). In some instances, for example, on a seldom-used mobile telephone, a subscriber might not care to have nor want to pay for an MWI displayed on the telephone. In this example, the subscriber has opted for the MWI feature on two telephone lines, 404-332-212X and 404-792-123X.
Once messaging service provider 100 receives an unanswered call to one of the three telephone numbers and records a message, messaging service provider 100 sends an MWI message for each of the activated telephone numbers on list 102, For the wireline telephone number, messaging service provider 100 transmits an MWI message to a host switch 104 using Inter-switch Simplified Message Desk Interface (ISMDI). Host switch 104 is a central office switch. ISMDI is a signaling interface used by a messaging service provider to support incoming call and message waiting integration between all supported switches in a Local Access and Transport Area (LATA). Simplified Message Desk Interface (SMDI) defines signaling between a messaging system and a central office switch, which defines the original intended destination of a forwarded call.
After receiving an MWI message for the wireline telephone number 404-332-212X, host switch 104 determines if it “owns” (i.e., is associated with) the NPA/NXX (NPA—Numbering Plan Area/NXX—a specific central office) corresponding to the telephone number, and further, if it owns the particular number (last four digits). In this example, host switch 104 does own 404-332-212X. Therefore, host switch 104 activates an MWI on the subscriber's wireline telephone 106, which could be a stutter dial tone, for example.
For the wireless telephone number 404-792-123X, messaging service provider 100 forwards to host switch 104 an ISMDI MWI message that references the wireless telephone number. Host switch 104 determines that it does not own 404-792, and in response, forwards to a signal transfer point 108 an MWI message using a non-call-associated Signaling System 7 (SS7) signaling protocol, such as Transaction Capability Application Part (TCAP).
Wireline network signal transfer point 108 contains a table 110 that cross-references NPA/NXXs with network point codes. Point codes identify every node in the SS7 network in the format NKN CCC XXX, where NNN is a network identifier, CCC is a cluster identifier, and XXX is the node identifier. In this example, table 110 shows that 404-792 corresponds to point code 001.002.052. With this routing information, wireline network signal transfer point 108 transmits a TCAP message to wireless network signal transfer point 112, which services the wireless network 114 corresponding to point code 001.002.052. In this example, wireless network 114 is the foreign network.
Within wireless network 114, protocol gateway 116 translates the TCAP MWI message to a signaling protocol compatible with the wireless network, for example, Interim Standard 41 (IS41). After the translation, protocol gateway 116 transmits an MWI message through mobile switching center 118 and antenna 120 to the subscriber's wireless telephone 122. In response to the MWI message, wireless telephone 122 indicates that a message has been recorded in messaging service provider 100 by, for example, displaying an icon on its screen.
According to the conventional method shown in FIG. 1, routing is based on the 6-digit NPA/NXX, relying on the fact that the networks to which the foreign network telephone numbers belong (which, in this example, are wireless telephone numbers of a wireless network) can be identified based solely on the NPA/NXX. In other words, the method assumes that each NPA/NXX, as a block of 10,000 telephone numbers, is wholly owned by a single foreign network carrier (e.g., a single wireless carrier). Under this assumption, the host wireline telephone network can route all calls for a NPA/NXX to a particular trunk group of a foreign network carrier.
Unfortunately, not all NPA/NXXs are wholly owned by a single carrier. In fact, within a block of 10,000 telephone numbers in a NPA/NXX, some numbers may be assigned to the wireline network, some may be assigned to a wireless network, and still others may be assigned to other wireline and wireless networks. As used herein, a “shared NPA/NXX” refers to this situation, in which the block of 10,000 telephone numbers in an NPA/NXX is assigned to more than one entity. Therefore, to forward message waiting indicator messages to the proper foreign network carrier of a particular foreign network telephone number, the routing network must distinguish the foreign network telephone numbers from the other network numbers on a more granular basis. In other words, the routing network must identify the different networks to which individual telephone numbers within a single shared NPA/NXX belong.